Acoustic microscopy techniques for structural ceramics

Through-transmission acoustic microscopy techniques employing 100-MHz ultrasonic waves are evaluated for their effectiveness in detecting and characterizing surface and subsurface defects in silicon carbide and silicon nitride components. Destructive examinations as well as radiographic techniques are used to confirm the presence of acoustically indicated defects. The sensitivity of the technique is demonstrated by means of acoustic micrographs of small (< 100 ..mu..m) artificial and naturally occurring defects. In addition, the microstructure of specimens as revealed by optical techniques is compared with the acoustic micrographs.